How to Test a Sump Pump (Before You Need It)
A sump pump only matters when it works during a storm. Here's how to test yours in five minutes, what a failed test means, and why a backup matters.
A sump pump is insurance you can't see working — until the one night it doesn't. It sits quietly in a pit in your basement and only earns its keep during heavy rain or snowmelt. That's why testing it before your wet season is one of the highest-stakes five-minute jobs a homeowner has.
Why it matters
When groundwater rises, the sump pump pumps it out before it floods your basement. A failed pump during a storm means inches of water, ruined belongings, and a mold problem. Most failures are discovered too late — during the flood — when a simple test would have caught them weeks earlier.
The five-minute test
- Find the sump pit — usually a covered hole in the lowest part of the basement or crawl space.
- Confirm it's plugged in and the cord isn't damaged. (You'd be surprised how often a pump is quietly unplugged.)
- Slowly pour a bucket of water into the pit until the float rises.
- Watch the pump kick on. It should start automatically, pump the water down quickly, and shut itself off when the float drops.
- Listen and look: the discharge should carry water outside, away from the foundation. No grinding, no rattling, no running-on after the pit is empty.
What a failed test means
- Nothing happens: the float may be stuck, the switch failed, or it lost power. Check the float moves freely first.
- Runs but moves no water: the discharge line may be clogged or frozen, or the impeller is jammed.
- Won't shut off: the float switch is stuck on — it will burn out the motor if left.
Any of these is fixable, but only if you find it before the storm.
Don't skip the backup
The cruel irony of sump pumps is that the storms most likely to flood you are also the ones most likely to cut your power. A battery backup keeps the pump running through an outage. Test the backup battery too — it's the part most often found dead at the worst moment.
While you're down there
Check the check valve on the discharge line (it stops pumped water from draining back into the pit) and make sure the discharge exits well away from the foundation, not right beside it. When the pump itself is aging, know the signs it's time to replace it.
Make it automatic
Build your free Owner Tools and we'll schedule the sump-pump test for the right time before your wet season — along with the backup-battery check and everything else. No login, no address required.